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SARS-CoV-2 is closely related to the original SARS-CoV. It is thought to have an animal (zoonotic) origin. Genetic analysis has revealed that the coronavirus genetically clusters with the genus Betacoronavirus, in subgenus Sarbecovirus (lineage B) together with two bat-derived strains. It is 96% identical at the whole ... | COVID-19 | Wikipedia | 494 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
, there are five dominant variants of SARS-CoV-2 spreading among global populations: the Alpha variant (B.1.1.7, formerly called the UK variant), first found in London and Kent, the Beta variant (B.1.351, formerly called the South Africa variant), the Gamma variant (P.1, formerly called the Brazil variant), the Delta v... | COVID-19 | Wikipedia | 509 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Nervous system
One common symptom, loss of smell, results from infection of the support cells of the olfactory epithelium, with subsequent damage to the olfactory neurons. The involvement of both the central and peripheral nervous system in COVID‑19 has been reported in many medical publications. It is clear that many... | COVID-19 | Wikipedia | 429 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Cardiovascular system
The virus can cause acute myocardial injury and chronic damage to the cardiovascular system. An acute cardiac injury was found in 12% of infected people admitted to the hospital in Wuhan, China, and is more frequent in severe disease. Rates of cardiovascular symptoms are high, owing to the system... | COVID-19 | Wikipedia | 390 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Although SARS-CoV-2 has a tropism for ACE2-expressing epithelial cells of the respiratory tract, people with severe COVID‑19 have symptoms of systemic hyperinflammation. Clinical laboratory findings of elevated IL2, IL6, IL7, as well as the following suggest an underlying immunopathology:
Granulocyte-macrophage colony... | COVID-19 | Wikipedia | 415 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Multiple viral and host factors affect the pathogenesis of the virus. The S-protein, otherwise known as the spike protein, is the viral component that attaches to the host receptor via the ACE2 receptors. It includes two subunits: S1 and S2.
S1 determines the virus-host range and cellular tropism via the receptor-bind... | COVID-19 | Wikipedia | 484 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
The severity of the inflammation can be attributed to the severity of what is known as the cytokine storm. Levels of interleukin1B, interferon-gamma, interferon-inducible protein 10, and monocyte chemoattractant protein1 were all associated with COVID‑19 disease severity. Treatment has been proposed to combat the cytok... | COVID-19 | Wikipedia | 504 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
However, from the evidence base, it is difficult to conclude whether pregnant women are at increased risk of grave consequences of this virus.
In addition to the above, other clinical studies have proved that SARS-CoV-2 can affect the period of pregnancy in different ways. On the one hand, there is little evidence of ... | COVID-19 | Wikipedia | 481 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
The University of Oxford's CEBM has pointed to mounting evidence that "a good proportion of 'new' mild cases and people re-testing positives after quarantine or discharge from hospital are not infectious, but are simply clearing harmless virus particles which their immune system has efficiently dealt with" and have cal... | COVID-19 | Wikipedia | 429 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Pathology
The main pathological findings at autopsy are:
Macroscopy: pericarditis, lung consolidation and pulmonary oedema
Lung findings:
Minor serous exudation, minor fibrin exudation
Pulmonary oedema, pneumocyte hyperplasia, large atypical pneumocytes, interstitial inflammation with lymphocytic infiltration and ... | COVID-19 | Wikipedia | 414 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
The first COVID‑19 vaccine was granted regulatory approval on 2December 2020 by the UK medicines regulator MHRA. It was evaluated for emergency use authorisation (EUA) status by the US FDA, and in several other countries. Initially, the US National Institutes of Health guidelines do not recommend any medication for pre... | COVID-19 | Wikipedia | 465 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Thorough hand hygiene after any cough or sneeze is required. The WHO also recommends that individuals wash hands often with soap and water for at least twenty seconds, especially after going to the toilet or when hands are visibly dirty, before eating and after blowing one's nose. When soap and water are not available,... | COVID-19 | Wikipedia | 471 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
The amount of time that the virus can survive depends significantly on the type of surface, the temperature, and the humidity. Coronaviruses die very quickly when exposed to the UV light in sunlight. Like other enveloped viruses, SARS-CoV-2 survives longest when the temperature is at room temperature or lower, and when... | COVID-19 | Wikipedia | 478 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Self-isolation at home has been recommended for those diagnosed with COVID‑19 and those who suspect they have been infected. Health agencies have issued detailed instructions for proper self-isolation. Many governments have mandated or recommended self-quarantine for entire populations. The strongest self-quarantine in... | COVID-19 | Wikipedia | 498 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Some early studies suggest 10% to 20% of people with COVID‑19 will experience symptoms lasting longer than a month. A majority of those who were admitted to hospital with severe disease report long-term problems including fatigue and shortness of breath. On 30 October 2020, WHO chief Tedros Adhanom warned that "to a si... | COVID-19 | Wikipedia | 466 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Men with untreated hypogonadism were 2.4 times more likely than men with eugonadism to be hospitalised if they contracted COVID-19; Hypogonad men treated with testosterone were less likely to be hospitalised for COVID-19 than men who were not treated for hypogonadism.
Genetic risk factors
Genetics plays an important ... | COVID-19 | Wikipedia | 481 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
By a variety of mechanisms, the lungs are the organs most affected in COVID19. In people requiring hospital admission, up to 98% of CT scans performed show lung abnormalities after 28 days of illness even if they had clinically improved. People with advanced age, severe disease, prolonged ICU stays, or who smoke are mo... | COVID-19 | Wikipedia | 425 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
As of August 2021, reinfection with COVID‑19 was possible but uncommon. The first case of reinfection was documented in August 2020. A systematic review found 17 cases of confirmed reinfection in medical literature as of May 2021. With the Omicron variant, as of 2022, reinfections have become common, albeit it is uncle... | COVID-19 | Wikipedia | 436 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
A December 2020 systematic review and meta-analysis estimated that population IFR during the first wave of the pandemic was about 0.5% to 1% in many locations (including France, Netherlands, New Zealand, and Portugal), 1% to 2% in other locations (Australia, England, Lithuania, and Spain), and exceeded 2% in Italy. Tha... | COVID-19 | Wikipedia | 259 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Earlier estimates of IFR
At an early stage of the pandemic, the World Health Organization reported estimates of IFR between 0.3% and 1%. On 2July, The WHO's chief scientist reported that the average IFR estimate presented at a two-day WHO expert forum was about 0.6%. In August, the WHO found that studies incorporating... | COVID-19 | Wikipedia | 387 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
The Chinese Center for Disease Control and Prevention reported the death rate was 2.8% for men and 1.7% for women. Later reviews in June 2020 indicated that there is no significant difference in susceptibility or in CFR between genders. One review acknowledges the different mortality rates in Chinese men, suggesting th... | COVID-19 | Wikipedia | 475 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Leaders have called for efforts to research and address the disparities. In the UK, a greater proportion of deaths due to COVID‑19 have occurred in those of a Black, Asian, and other ethnic minority background. More severe impacts upon patients including the relative incidence of the necessity of hospitalisation requir... | COVID-19 | Wikipedia | 386 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Most critical respiratory comorbidities according to the US Centers for Disease Control and Prevention (CDC), are: moderate or severe asthma, pre-existing COPD, pulmonary fibrosis, cystic fibrosis. Evidence stemming from meta-analysis of several smaller research papers also suggests that smoking can be associated with ... | COVID-19 | Wikipedia | 414 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Most scientists believe the virus spilled into human populations through natural zoonosis, similar to the SARS-CoV-1 and MERS-CoV outbreaks, and consistent with other pandemics in human history. According to the Intergovernmental Panel on Climate Change several social and environmental factors including climate change,... | COVID-19 | Wikipedia | 441 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
By December 2019, the spread of infection was almost entirely driven by human-to-human transmission. The number of COVID-19 cases in Hubei gradually increased, reaching sixty by 20 December, and at least 266 by 31 December. On 24 December, Wuhan Central Hospital sent a bronchoalveolar lavage fluid (BAL) sample from an ... | COVID-19 | Wikipedia | 494 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Italy had its first confirmed cases on 31 January 2020, two tourists from China. Italy overtook China as the country with the most deaths on 19 March 2020. By 26 March the United States had overtaken China and Italy with the highest number of confirmed cases in the world. Research on coronavirus genomes indicates the m... | COVID-19 | Wikipedia | 456 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Some pets, especially cats and ferrets, can catch this virus from infected humans. Symptoms in cats include respiratory (such as a cough) and digestive symptoms. Cats can spread the virus to other cats, and may be able to spread the virus to humans, but cat-to-human transmission of SARS-CoV-2 has not been proven. Compa... | COVID-19 | Wikipedia | 387 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Modelling research has been conducted with several objectives, including predictions of the dynamics of transmission, diagnosis and prognosis of infection, estimation of the impact of interventions, or allocation of resources. Modelling studies are mostly based on compartmental models in epidemiology, estimating the nu... | COVID-19 | Wikipedia | 508 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
In September 2020, the WHO released updated guidance on using corticosteroids for COVID‑19. The WHO recommends systemic corticosteroids rather than no systemic corticosteroids for the treatment of people with severe and critical COVID‑19 (strong recommendation, based on moderate certainty evidence). The WHO suggests no... | COVID-19 | Wikipedia | 474 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
A cytokine storm can be a complication in the later stages of severe COVID‑19. A cytokine storm is a potentially deadly immune reaction where a large amount of pro-inflammatory cytokines and chemokines are released too quickly. A cytokine storm can lead to ARDS and multiple organ failure. Data collected from Jin Yin-ta... | COVID-19 | Wikipedia | 484 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
Transferring purified and concentrated antibodies produced by the immune systems of those who have recovered from COVID‑19 to people who need them is being investigated as a non-vaccine method of passive immunisation. Viral neutralisation is the anticipated mechanism of action by which passive antibody therapy can medi... | COVID-19 | Wikipedia | 475 | 63030231 | https://en.wikipedia.org/wiki/COVID-19 | Biology and health sciences | Viral diseases | Health |
MicroLED, also known as micro-LED, mLED or μLED is an emerging flat-panel display technology consisting of arrays of microscopic LEDs forming the individual pixel elements. Inorganic semiconductor microLED (μLED) technology was first invented in 2000 by the research group of Hongxing Jiang and Jingyu Lin of Texas Tech ... | MicroLED | Wikipedia | 451 | 47562547 | https://en.wikipedia.org/wiki/MicroLED | Technology | Media and communication: Basics | null |
Research
Following the first report of electrical injection microLEDs based on indium gallium nitride (InGaN) semiconductors in 2000 by the research group of Hongxing Jiang and Jingyu Lin, several groups have quickly engaged in pursuing this concept. Many related potential applications have been identified. Various on-... | MicroLED | Wikipedia | 299 | 47562547 | https://en.wikipedia.org/wiki/MicroLED | Technology | Media and communication: Basics | null |
There are several methods to manufacture microLED displays. The flip-chip method manufactures the LED on a conventional sapphire substrate, while the transistor array and solder bumps are deposited on silicon wafers using conventional manufacturing and metallization processes. Mass transfer is used to pick and place se... | MicroLED | Wikipedia | 457 | 47562547 | https://en.wikipedia.org/wiki/MicroLED | Technology | Media and communication: Basics | null |
Digital pulse-width modulation is well-suited to driving microLED displays. MicroLEDs experience a color shift as the current magnitude changes. Analog schemes change current to change brightness. With a digital pulse, only one current value is used for the on state. Thus, there is no color shift that occurs as brightn... | MicroLED | Wikipedia | 491 | 47562547 | https://en.wikipedia.org/wiki/MicroLED | Technology | Media and communication: Basics | null |
At SID's Display Week 2019 in May, Tianma and PlayNitride demonstrated their co-developed microLED display with over 60% transparency. China Star Optoelectronics Technology (CSoT) demonstrated a transparent microLED display with around 45% transparency, also co-developed with PlayNitride. Plessey Semiconductors Ltd d... | MicroLED | Wikipedia | 492 | 47562547 | https://en.wikipedia.org/wiki/MicroLED | Technology | Media and communication: Basics | null |
Antigone is a genus of large birds in the crane family. The species in this genus were formerly placed in the genus Grus.
Taxonomy
The genus was named by Carl Linnaeus to be used for the sarus crane or its old name Grus major Indica because he was confused between Greek princesses Antigone of Troy who turned into a s... | Antigone (bird) | Wikipedia | 159 | 51664225 | https://en.wikipedia.org/wiki/Antigone%20%28bird%29 | Biology and health sciences | Gruiformes | Animals |
Be stars are a heterogeneous set of stars with B spectral types and emission lines. A narrower definition, sometimes referred to as classical Be stars, is a non-supergiant B star whose spectrum has, or had at some time, one or more Balmer emission lines.
Definition and classification
Many stars have B-type spectra an... | Be star | Wikipedia | 470 | 47577681 | https://en.wikipedia.org/wiki/Be%20star | Physical sciences | Stellar astronomy | Astronomy |
Be stars are often visually and spectroscopically variable. Be stars can be classified as Gamma Cassiopeiae variables when a transient or variable disk is observed. Be stars that show variability without clear indication of the mechanism are listed simply as BE in the General Catalogue of Variable Stars. Some of the... | Be star | Wikipedia | 78 | 47577681 | https://en.wikipedia.org/wiki/Be%20star | Physical sciences | Stellar astronomy | Astronomy |
Approximate measures are units of volumetric measurement which are not defined by a government or government-sanctioned organization, or which were previously defined and are now repealed, yet which remain in use.
It may be that all English-unit derived capacity measurements are derived from one original approximate m... | Approximate measures | Wikipedia | 399 | 51711705 | https://en.wikipedia.org/wiki/Approximate%20measures | Physical sciences | Measurement systems | Basics and measurement |
United States
The vagueness of how these measures have been defined, redefined, and undefined over the years, both through written and oral history, is best exemplified by the large number of sources that need to be read and cross-referenced in order to paint even a reasonably accurate picture. So far, the list include... | Approximate measures | Wikipedia | 303 | 51711705 | https://en.wikipedia.org/wiki/Approximate%20measures | Physical sciences | Measurement systems | Basics and measurement |
Argon compounds, the chemical compounds that contain the element argon, are rarely encountered due to the inertness of the argon atom. However, compounds of argon have been detected in inert gas matrix isolation, cold gases, and plasmas, and molecular ions containing argon have been made and also detected in space. One... | Argon compounds | Wikipedia | 502 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Ar+ + H2 → *ArH+ + H 1.49 eV.
When ArH+ encounters an electron, dissociative recombination can occur, but it is extremely slow for lower energy electrons, allowing ArH+ to survive for a much longer time than many other similar protonated cations.
ArH+ + e− → ArH* → Ar + H
Artificial ArH+ made from earthly Ar contain... | Argon compounds | Wikipedia | 354 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Larger charged argon clusters are also detectable in mass spectroscopy. The tetraargon cation is also linear. icosahedral clusters have an core, whereas is dioctahedral with an core. The linear core has +0.1 charge on the outer atoms, and +0.4 charge on each or the inner atoms. For larger charged argon clusters, t... | Argon compounds | Wikipedia | 503 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Formation: Ar + ν → Ar*; Ar* + H2 → ArH* + H
Instead of dihydrogen, other hydrogen containing molecules can also have a hydrogen atom abstracted by excited argon, but note that some molecules bind hydrogen too strongly for the reaction to proceed. For example, acetylene will not form ArH this way.
In the van der Waal... | Argon compounds | Wikipedia | 136 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
The spectrum of argon monohydride, both ArH* and ArD*, has been studied. The lowest bound state is termed A2Σ+ or 5s. Another low lying state is known as 4p, made up of C2Σ+ and B2π states. Each transition to or from higher level states corresponds to a band. Known bands are 3p → 5s, 4p → 5s, 5p → 5s (band origin ), 6p... | Argon compounds | Wikipedia | 383 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Other ways to make ArH include a Penning-type discharge tube, or other electric discharges. Yet another way is to create a beam of ArH+ (argonium) ions and then neutralize them in laser-energized caesium vapour. By using a beam, the lifetimes of the different energy states can be observed, by measuring the profile of e... | Argon compounds | Wikipedia | 511 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Argon dinitrogen cation
The argon dinitrogen linear cationic complex has also been detected in the lab:
Ar + → Ar+ + N2.
The dissociation yields Ar+, as this is a higher-energy state. The binding energy is 1.19 eV. The molecule is linear. The distance between two nitrogen atoms is 1.1 Å. This distance is similar to ... | Argon compounds | Wikipedia | 491 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
ArHCO+
ArHCO+ has been produced in a supersonic-jet expansion of gas and detected by Fabry–Perot-type Fourier transform microwave spectroscopy.
The molecule is made by this reaction
ArH+ + CO → ArHCO+.
ArnBO+
BO+ forms four complexes with argon: ArBO+; two isomers of Ar2BO+ (one with equidistant Ar-B bonds and anoth... | Argon compounds | Wikipedia | 433 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
In addition to the very weakly bound van der Waals molecules, electronically excited molecules with the same formula exist. As a formula these can be written ArX*, with the "*" indicating an excited state. The atoms are much more strongly bound with a covalent bond. They can be modeled as an ArX+ surrounded by a higher... | Argon compounds | Wikipedia | 350 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Diatomic van der Waals molecules
{|class="wikitable"
!Molecule
!Binding energyground Σ state(cm−1)
!Binding energyexcited Π state(cm−1)
!Ground statebond length(Å)
!Excited statebond length(Å)
!CAS number
|-
|ArH
|
|
|
|
|30736-04-0
|-
|ArHe
|
|
|
|
|12254-69-2
|-
|LiAr
|42.5
|925
|4.89
|2.48
|
|-
|BAr
|
|
|
|
|149358-... | Argon compounds | Wikipedia | 486 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
ArO* is also formed when dioxygen trapped in an argon matrix is subjected to vacuum ultraviolet. It can be detected by its luminescence:
O2 + hv → + e−; + e− → 2O*; O* + Ar → ArO*.
Light emitted by ArO* has two main bands, one at 2.215 eV, and a weaker one at 2.195 eV.
Argon sulfide, ArS* luminesces in the near infr... | Argon compounds | Wikipedia | 511 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
ArBH was produced from boron monohydride (BH) which in turn was created from diborane by way of an ultraviolet 193 nm laser. The BH-argon mixture was expanded through a 0.2 mm diameter nozzle into a vacuum. The gas mixture cools and Ar and BH combine to yield ArBH. A band spectrum that combines the A1Π←X1Σ+ electronic ... | Argon compounds | Wikipedia | 314 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
{|class="wikitable"
!Molecule
!Name
!Ground statebinding energy(cm−1)
!Closest position or atomto argon
!Ground statebond length of Ar(Å)
!Bond anglefrom atom(degrees)
!Bond stretch force or frequency
!dipole moment D
!CAS number
!references
|-
|(CH3)2F2Si·Ar
| Difluorodimethylsilane – argon
|
|
|
|
|
|
|
|
|-
|CH2F2·A... | Argon compounds | Wikipedia | 505 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
|argon-deuterated acetylene
|
|centre of molecule
|3.25
|90° T shape
|0.0008 mdyn/Å / 8.7 cm−1
|
|
|
|-
|SO3Ar
|sulfur trioxide argon
|
|S
|3.350
|on axis 90° from SO bond
|0.059 mdyn/Å / 61 cm−1
|
|
|
|-
|Ar•HCCH
|acetylene argon
|
|
|
|T shape
|
|
|
|
|-
|OCS•Ar|| || || || || || || || ||
|-
|CH3OH•Ar|| || || || || ||... | Argon compounds | Wikipedia | 239 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Aqueous argon
Argon dissolved in water causes the pH to rise to 8.0, apparently by reducing the number of oxygen atoms available to bind protons.
With ice, argon forms a clathrate hydrate. Up to 0.6 GPa, the clathrate has a cubic structure. Between 0.7 and 1.1 GPa the clathrate has a tetragonal structure. Between 1.1 ... | Argon compounds | Wikipedia | 251 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Uranium compounds
CUO in a solid argon matrix can bind one, or a few argon atoms to yield CUO·Ar, CUO·Ar3 or CUO·Ar4. CUO itself is made by evaporating uranium atoms into carbon monoxide. Uranium acts as a strong Lewis acid in CUO and forms bonds with energies of about 3.2 kcal/mol (13.4 kJ/mol) with argon. The argon a... | Argon compounds | Wikipedia | 397 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
can bind up to five noble gas atoms in a ring around a linear O==O core. These molecules are produced when uranium metal is laser ablated into dioxygen. This produces UO, UO2, UO3, U+, and importantly . is then condensed into a noble gas matrix, either a pure element or a mixture. Heavier noble gas atoms will tend to ... | Argon compounds | Wikipedia | 507 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Carbonyl compounds
Group 6 elements can form reactive pentacarbonyls that can react with argon. These were actually argon compounds discovered in 1975, and were known before the discovery of HArF, but are usually overlooked. Tungsten normally forms a hexacarbonyl, but when subject to ultraviolet radiation it breaks int... | Argon compounds | Wikipedia | 437 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Attempts have been made to study carbonyl–argon adducts in the gas phase, but the interaction appears to be too weak to observe a spectrum. In the gas form, the absorption lines are broadened into bands because of rotation that happens freely in a gas. The argon adducts in liquids or gases are unstable as the molecules... | Argon compounds | Wikipedia | 398 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
In the case of transition metal monoxides, ScO, TiO and VO do not form a molecule with one argon atom. However CrO, MnO, FeO, CoO and NiO can each coordinate one argon atom in a solid argon matrix. The metal monoxide molecules can be produced by laser ablation of the metal trioxide, followed by condensation on solid ar... | Argon compounds | Wikipedia | 447 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
ArF+ is also known to be formed in the reaction
+ Ar → ArF+ + F
and also
Ar+ + F2 → ArF+ + F.
and also
SF + Ar → ArF+ + SF.
The ions can be produced by ultraviolet light at 79.1 nm or less. The ionisation energy of fluorine is higher than that of argon, so breakup occurs thus:
ArF+ → Ar+ + F.
The millimeter wave spect... | Argon compounds | Wikipedia | 504 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
ArN+ can form when argon ions impact dinitrogen with energies between 8.2 and 41.2 eV and peaking around 35 eV. However far more and N+ are produced.
ArXe+ is held together with a strength of 1445 cm−1 when it is in the X electronic state, but 1013 cm−1 when it is in the B excited state.
Metal–argon cations are call... | Argon compounds | Wikipedia | 279 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
{|class="wikitable"
!Ion
!Bond length(Å)
!Dissociation energy(kJ/mol)
!Excited statebond length (Å)
!Excited statedissociation energy
|-
|ArH+
|
|3.4 eV
|-
|LiAr+
|2.343
|0.30 eV
|-
|BeAr+
|
|4100 cm−1
|-
|BAr+
|2.590
|210
|-
|ArC+
|
|
|-
|ArN+
|3.5
|2.16 eV
|-
|ArO+
|
|
|-
|ArF+
|1.637
|194
|-
|NaAr+
|
|19.3
|-
|MgAr+... | Argon compounds | Wikipedia | 489 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Metal ions can also form with more than one argon atom, in a kind of argon metal cluster. Different sized metal ions at the centre of a cluster can fit different geometries of argons atoms around the ion. Argides with multiple argon atoms have been detected in mass spectrometry. These can have variable numbers of argo... | Argon compounds | Wikipedia | 349 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Sodium forms clusters with argon atoms with peaks at numbers of 8, 10, 16, 20, 23, 25 and 29, and also at the icosahedral numbers of 47, 50, 57, 60, 63, 77, 80, 116 and 147 argon atoms. This includes the square antiprism (8) and the capped square antiprism (10 atoms).
In Ti+Ar1−n the argon atoms induce a mixing of the ... | Argon compounds | Wikipedia | 465 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
With a strontium ion Sr+ from two to eight argon atoms can form clusters. Sr+Ar2 has a triangle shape with C2v symmetry. Sr+Ar3 has a trigonal pyramid shape with C3v symmetry. Sr+Ar4 has two trigonal pyramids sharing a face and strontium at the common apex. It has a C2v symmetry. Sr+Ar6 has a pentagonal pyramid of argo... | Argon compounds | Wikipedia | 217 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
By zapping copper metal with a UV laser in an argon-carbon monoxide mixture, argon tagged copper carbonyl cations are formed. These ions can be studied by observing which wavelengths of infrared radiation cause the molecules to break up. These molecular ions include CuCO+Ar, Cu(CO)2+Ar, Cu(CO)3+Ar, Cu(CO)4+Ar which are... | Argon compounds | Wikipedia | 482 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Boroxyl ring cationic complexes with argon [ArB3O4]+, [ArB3O5]+, [ArB4O6]+ and [ArB5O7]+ were prepared via a laser vaporization at cryogenic temperatures and investigated by infrared gas phase spectroscopy. They were the first large stable gas phase complexes that feature strong dative bonding between argon and boron.
... | Argon compounds | Wikipedia | 501 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Fullerene solvates
Solid buckminsterfullerene has small spaces between the C60 balls. Under 200 MPa pressure and 200 °C heat for 12 hours, argon can be intercalated into the solid to form crystalline Ar1C60. Once this cools down it is stable at standard conditions for months. Argon atoms occupy octahedral interstitial ... | Argon compounds | Wikipedia | 489 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Argon difluoride
Argon difluoride, ArF2, is predicted to be stable at pressures over 57 GPa. It should be an electrical insulator.
Ne2Ar and Ar2Ne
At around 4 K there are two phases where neon and argon are mixed as a solid: Ne2Ar and Ar2Ne. With Kr, solid argon forms a disorganized mixture.
ArH4
Under high pressure ... | Argon compounds | Wikipedia | 418 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Ar-TON
Under pressure argon inserts into zeolite. Argon has an atomic radius of 1.8 Å, so it can insert into pores if they are big enough. Each unit cell of the TON zeolite can contain up to 5 atoms of argon, compared to 12 of neon. Argon infused TON zeolite (Ar-TON) is more compressible than Ne-TON as the unoccupied p... | Argon compounds | Wikipedia | 360 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
The compound FArCCH has been theoretically studied and is predicted to be stable. FArCCF might also be stable enough to synthesise and detect, but probably not FArCCArF. Calculations in 2015 suggest that FArCCH and FArCH3 are stable, but not FArCN. should be kinetically stable, as is also expected of the krypton and x... | Argon compounds | Wikipedia | 239 | 51721949 | https://en.wikipedia.org/wiki/Argon%20compounds | Physical sciences | Noble gas compounds | Chemistry |
Climate change in the Middle East and North Africa (MENA) refers to changes in the climate of the MENA region and the subsequent response, adaption and mitigation strategies of countries in the region. In 2018, the MENA region emitted 3.2 billion tonnes of carbon dioxide and produced 8.7% of global greenhouse gas emiss... | Climate change in the Middle East and North Africa | Wikipedia | 489 | 63074081 | https://en.wikipedia.org/wiki/Climate%20change%20in%20the%20Middle%20East%20and%20North%20Africa | Physical sciences | Climate change | Earth science |
Greenhouse gas emissions produced by humans have been identified by the IPCC and the vast majority of climate scientists as the primary driver of climate change. In the past three decades, the MENA region has more than tripled its greenhouse gas emissions and is currently emitting above the global average per person, w... | Climate change in the Middle East and North Africa | Wikipedia | 274 | 63074081 | https://en.wikipedia.org/wiki/Climate%20change%20in%20the%20Middle%20East%20and%20North%20Africa | Physical sciences | Climate change | Earth science |
Heat extremes
The IPCC project average global temperatures to rise more than 1.5 degrees by the end of the 21st century. MENA has been identified as a hotspot for future temperature changes due to its arid environmental conditions. Whilst projected rates of warming during winter months are low, the region is expected ... | Climate change in the Middle East and North Africa | Wikipedia | 396 | 63074081 | https://en.wikipedia.org/wiki/Climate%20change%20in%20the%20Middle%20East%20and%20North%20Africa | Physical sciences | Climate change | Earth science |
Water resources
The Middle East and North Africa currently faces extreme water scarcity, with twelve out of the 17 most water stressed countries in the world deriving from the region. The World Bank defines an area as being water stressed when per person water supplies fall below 1,700 cubic metres per year. The water... | Climate change in the Middle East and North Africa | Wikipedia | 449 | 63074081 | https://en.wikipedia.org/wiki/Climate%20change%20in%20the%20Middle%20East%20and%20North%20Africa | Physical sciences | Climate change | Earth science |
Increasing water insecurity as a result of climate change is set to exacerbate existing food insecurities in the countries affected. A study published by the World Food Programme has predicted a decline in crop yields by 30% in 2050 as a result of increasing droughts. North African countries are highly vulnerable to re... | Climate change in the Middle East and North Africa | Wikipedia | 502 | 63074081 | https://en.wikipedia.org/wiki/Climate%20change%20in%20the%20Middle%20East%20and%20North%20Africa | Physical sciences | Climate change | Earth science |
The MENA region possesses high potential for developing renewable energy technologies due to the high levels of wind and sunshine that are associated with its climate. The International Renewable Energy Agency (IRENA) has identified over half of all land in GCC states as being suitable for the deployment of solar and ... | Climate change in the Middle East and North Africa | Wikipedia | 364 | 63074081 | https://en.wikipedia.org/wiki/Climate%20change%20in%20the%20Middle%20East%20and%20North%20Africa | Physical sciences | Climate change | Earth science |
Eleven countries from the MENA region attended the 21st Conference of the Parties of the UNFCCC where countries negotiated the Paris Agreement, an agreement with the United Nations concerning greenhouse gas emissions mitigation. Eritrea, Iran, Iraq, Libya, and Yemen are the only countries in the world which have not r... | Climate change in the Middle East and North Africa | Wikipedia | 392 | 63074081 | https://en.wikipedia.org/wiki/Climate%20change%20in%20the%20Middle%20East%20and%20North%20Africa | Physical sciences | Climate change | Earth science |
Israel
According to the Ministry of Environmental Protection of Israel: "While Israel is a relatively small contributor to climate change due to its size and population, it is sensitive to the potential impacts of the phenomenon, due to its location. Thus, it is making an effort to reduce greenhouse gas emissi... | Climate change in the Middle East and North Africa | Wikipedia | 438 | 63074081 | https://en.wikipedia.org/wiki/Climate%20change%20in%20the%20Middle%20East%20and%20North%20Africa | Physical sciences | Climate change | Earth science |
A lithophane is a thin plaque of translucent material, normally porcelain, which has been moulded to varying thickness, such that when lit from behind the different thicknesses show as different shades, forming an image. Only when lit from behind does the image display properly. They were invented in the 19th century ... | Lithophane | Wikipedia | 499 | 73165062 | https://en.wikipedia.org/wiki/Lithophane | Technology | Materials | null |
As the porcelain is in places only about thick, wastage in firing was high, up to about 60%.
History
There were precedents in Chinese porcelain, in a technique known as an hua, meaning "secret" or "hidden decoration". But this seems to have been produced by scratching or engraving the unfired porcelain body, and wa... | Lithophane | Wikipedia | 461 | 73165062 | https://en.wikipedia.org/wiki/Lithophane | Technology | Materials | null |
Similar effects can be achieved in moulded coloured glass, but these should probably not be called lithophanes. The term has revived in use for images created by digitally-controlled cutting ("CNC"), a subtractive process, or by 3D printing, an additive one. Many companies now offer to make one-off images, or the equi... | Lithophane | Wikipedia | 148 | 73165062 | https://en.wikipedia.org/wiki/Lithophane | Technology | Materials | null |
Detrital zircon geochronology is the science of analyzing the age of zircons deposited within a specific sedimentary unit by examining their inherent radioisotopes, most commonly the uranium–lead ratio. Zircon is a common accessory or trace mineral constituent of most granite and felsic igneous rocks. Due to its hardne... | Detrital zircon geochronology | Wikipedia | 426 | 51726398 | https://en.wikipedia.org/wiki/Detrital%20zircon%20geochronology | Physical sciences | Geochronology | Earth science |
Zircon is a strong tool for uranium-lead age determination because of its inherent properties:
Zircon contains high amount of uranium for machine recognition, commonly 100–1000 ppm.
Zircon has a low amount of lead during crystallization, in parts per trillion. Thus, lead found in zircon can be assumed as daughter nuc... | Detrital zircon geochronology | Wikipedia | 270 | 51726398 | https://en.wikipedia.org/wiki/Detrital%20zircon%20geochronology | Physical sciences | Geochronology | Earth science |
Sample collection
There are no set rules for sample selection in detrital zircon geochronology studies. The objective and scale of the research project govern the type and number of samples taken. In some cases, the sedimentary rock type and depositional setting can significantly affect the result. Examples include:
... | Detrital zircon geochronology | Wikipedia | 479 | 51726398 | https://en.wikipedia.org/wiki/Detrital%20zircon%20geochronology | Physical sciences | Geochronology | Earth science |
Qualitative analysis
Qualitative approach examines all the available detrital zircons individually regardless of their abundance among all grains. This approach is usually conducted with high precision thermal ionization mass spectrometry (TIMS) and sometimes secondary ion mass spectrometry (SIMS). Optical examination... | Detrital zircon geochronology | Wikipedia | 433 | 51726398 | https://en.wikipedia.org/wiki/Detrital%20zircon%20geochronology | Physical sciences | Geochronology | Earth science |
By U-Pb age discordance
Before applying detrital zircon ages, they should be evaluated and screened accordingly. In most cases, data are compared with U-Pb Concordia graphically. For a large dataset, however, data with high U-Pb age discordance (>10 – 30%) are filtered out numerically. The acceptable discordance level... | Detrital zircon geochronology | Wikipedia | 394 | 51726398 | https://en.wikipedia.org/wiki/Detrital%20zircon%20geochronology | Physical sciences | Geochronology | Earth science |
By applied analytical methods
Depending on the required analytical accuracy, researchers may filter data via their analytical instruments. Generally, researchers use only the data from sensitive high-resolution ion microprobe (SHRIMP), inductively coupled plasma mass spectrometry (LA-ICPMS) and thermal ionization mass... | Detrital zircon geochronology | Wikipedia | 368 | 51726398 | https://en.wikipedia.org/wiki/Detrital%20zircon%20geochronology | Physical sciences | Geochronology | Earth science |
Using detrital zircon age abundance
In a global scale, detrital zircon age abundance can be used as a tool to infer significant tectonic events in the past. In Earth's history, the abundance of magmatic age peaks during periods of supercontinent assembly. This is because supercontinent provides a major crustal envelop... | Detrital zircon geochronology | Wikipedia | 268 | 51726398 | https://en.wikipedia.org/wiki/Detrital%20zircon%20geochronology | Physical sciences | Geochronology | Earth science |
Basic lead phosphite is an inorganic compound with the proposed composition Pb3O(OH)2(HPO3). The compound contains the phosphite anion, which provides the reducing properties associated with the application of this material.
It is widely used as a stabilizer for chlorine-containing polymers, especially polyvinylchlor... | Basic lead phosphite | Wikipedia | 106 | 54561126 | https://en.wikipedia.org/wiki/Basic%20lead%20phosphite | Physical sciences | Phosphoric oxyanions | Chemistry |
Uroplatinae is a subfamily of geckos in the family Gekkonidae. At least 28 genera have been found to be cluster in a clade together. In the past this was once a monotypic subfamily that included Uroplatus.
Below are the following genera: | Uroplatinae | Wikipedia | 56 | 64469899 | https://en.wikipedia.org/wiki/Uroplatinae | Biology and health sciences | Lizards and other Squamata | Animals |
HCL (Hue-Chroma-Luminance) or LCh refers to any of the many cylindrical color space models that are designed to accord with human perception of color with the three parameters. Lch has been adopted by information visualization practitioners to present data without the bias implicit in using varying saturation. They are... | HCL color space | Wikipedia | 491 | 47640103 | https://en.wikipedia.org/wiki/HCL%20color%20space | Physical sciences | Basics | Physics |
The HSL and HSV color spaces are more intuitive translations of the RGB color space, because they provide a single hue number. However, their luminance variation does not match the way humans perceive color. Perceptually uniform color spaces outperform RGB in cases such as high noise environments.
CIE color spaces
CI... | HCL color space | Wikipedia | 497 | 47640103 | https://en.wikipedia.org/wiki/HCL%20color%20space | Physical sciences | Basics | Physics |
A marine coastal ecosystem is a marine ecosystem which occurs where the land meets the ocean. Worldwide there is about of coastline. Coastal habitats extend to the margins of the continental shelves, occupying about 7 percent of the ocean surface area. Marine coastal ecosystems include many very different types of mar... | Marine coastal ecosystem | Wikipedia | 428 | 65970498 | https://en.wikipedia.org/wiki/Marine%20coastal%20ecosystem | Physical sciences | Oceanography | Earth science |
Directly and indirectly, marine coastal ecosystems provide vast arrays of ecosystem services for humans, such as cycling nutrients and elements, and purifying water by filtering pollutants. They sequester carbon as a cushion against climate change. They protect coasts by reducing the impacts of storms, reducing coastal... | Marine coastal ecosystem | Wikipedia | 455 | 65970498 | https://en.wikipedia.org/wiki/Marine%20coastal%20ecosystem | Physical sciences | Oceanography | Earth science |
In 2015, the United Nations established 17 Sustainable Development Goals with the aim of achieving certain targets by 2030. Their mission statement for their 14th goal, Life below water, is to "conserve and sustainably use the oceans, seas and marine resources for sustainable development". The United Nations has also d... | Marine coastal ecosystem | Wikipedia | 305 | 65970498 | https://en.wikipedia.org/wiki/Marine%20coastal%20ecosystem | Physical sciences | Oceanography | Earth science |
Estuaries occur where there is a noticeable change in salinity between saltwater and freshwater sources. This is typically found where rivers meet the ocean or sea. The wildlife found within estuaries is unique as the water in these areas is brackish - a mix of freshwater flowing to the ocean and salty seawater. Other ... | Marine coastal ecosystem | Wikipedia | 453 | 65970498 | https://en.wikipedia.org/wiki/Marine%20coastal%20ecosystem | Physical sciences | Oceanography | Earth science |
Coral reefs are one of the most well-known marine ecosystems in the world, with the largest being the Great Barrier Reef. These reefs are composed of large coral colonies of a variety of species living together. The corals from multiple symbiotic relationships with the organisms around them. Coral reefs are being heavi... | Marine coastal ecosystem | Wikipedia | 505 | 65970498 | https://en.wikipedia.org/wiki/Marine%20coastal%20ecosystem | Physical sciences | Oceanography | Earth science |
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